C/EBPβ transcription factor promotes alcohol-induced liver fibrosis in males via HDL remodeling

Alcohol-associated liver disease (ALD) is the main cause of alcohol-associated mortality. However, the mechanism of ALD development is poorly understood. Epigenetic changes are thought to play an important role in ALD. We aimed to define the epigenetic changes induced by alcohol and predict drivers of these changes.

Mice were fed high-fat diet with or without 20% of alcohol in the drinking water for 20 weeks (WDA model). scATAC-seq data set was analyzed using Signac R package. To test the role of C/EBPβ, Cebpb-floxed mice were treated with AAV8-TBG-Cre or AAV8-control.

We analyzed differentially accessible regions in livers from control and alcohol-fed mice and found that activity of C/EBPβ transcription factor was associated with alcohol-induced epigenetic changes in hepatocytes. C/EBPβ protein levels were significantly upregulated in multiple models of ALD and human ALD samples. Using hepatocyte-specific Cebpb knockout mice we found that Cebpb loss protected male mice from alcohol-induced fibrosis development. We found no protection in female mice, suggesting that this mechanism is specific to male ALD. In vitro studies suggested that the protective effect of Cebpb loss was mediated by altered hepatocyte-macrophage cross talk. Cebpb knockout in hepatocytes reduced a profibrotic and promoted a pro-resolving phenotype in macrophages, thus modulating ALD development. We further identified the mediators of the cross talk. Cebpb knockout altered the expression of several HDL protein components, increasing APOA1 and apolipoprotein M and reducing apolipoprotein E and SAA levels in male mice. HDL secreted by Cebpb knockout hepatocytes was sufficient to confer anti-inflammatory and antifibrotic changes to macrophages.

Taken together, alcohol-induced C/EBPβ activation is a key driver of ALD fibrosis in males via C/EBPβ-dependent HDL remodeling.